Conventional axle-hub assemblies include a stationary axle or spindle which supports spaced front and rear bearings which, in turn, support a rotatable hub. When greasing these axle-hub assemblies, and particularly those which may be submersed in water as, for example, in the situation of a hub assembly for a boat trailer, it is important that grease is applied to both the front and rear bearings and to otherwise effect a complete lubrication of the axle-hub assemblies.
To date, no system has been economically developed which conveniently and efficiently assures the user that the entire axle-hub assembly has been greased. One existing system requires that an axial bore be drilled substantially along the entire length of the spindle. Grease is applied into the axial bore through an opening in the end cap, travels through the entire axial bore and exits the same through radial bores in the spindle at a location behind the inner bearings. The grease then travels back through the inner bearings, between the hub and the spindle, through the outer bearings, and into the open end cap where it can be observed by the user indicating a complete greasing.
Such a system has been found to be deficient in many regards. First, the manufacture thereof is quite expensive requiring the time-consuming drilling of the axial bore and a special end cap having an aperture therein and means to seal the same. Further, application of the grease takes longer inasmuch as it must first travel from the end cap through the entire length of the spindle and then back to the end cap. In addition, with the grease entry and exit points being at the same general location, the messy discharge of grease onto the users hands cannot usually be avoided.
Another existing system is shown in U.S. Pat. No. 4,172,620. There, grease is introduced through the hub behind the wheel support portion thereof. The grease then passes through the inner bearing, then between the spindle and the hub, then through the outer bearings, and then out through a special opening in the end cap to provide an indication of complete greasing of the assembly. Such a system is inconvenient for the user in that he must reach blindly behind the wheel support portion of the hub to locate the grease fitting. Further, a special end cap is required to permit grease to pass therethrough, which passage also exposes the user to the grease.